Dual carburetor system



Feb.18,1947. T,M BAL,L ETA v 2,415,860

DUAL CARBURETOR SYSTEM Filed Jan. 18, 1943 INVENTORS THOMAS-M. BALL, and

BY WALLACE E. z 1 RER ATTORNEYS paratus therefor. V More particularlythe invention pertains to im- Patented Feb. 18, 1947 UNITED STATES PATsr OFF-ICE DUAL CARBURETOB SYSTEM Thomas M. Ball, Detroit, and Wallace E.Zierer,

Franklin, Mich, assignors to Chrysler Corporation, Highland Park, Mich,a corporation of Delaware Application January 18, 1943, serial it...472,66 j

1 This invention relates to an improved internal combustion engine fuelsystem and control approved control apparatus for the throttle valves ofthe carburetors of a dual carburetor system of the character which has apair of carburetors discharging fuel mixture fold. V i A on of the mainobjects of the invention is to into a, single intake maniprovide in adual carburetor system of this kind,

throttle control apparatus which, during initial throttle openinactuation positively opens the throttle valve of one carburetor,hereinafter referred to as No. l carburetor. and subsequentlyconditions-the throttle valve of the other carburetor, hereinaftercalled carburetor No. 2, to

open in response to the application of a. predetermined engine suctionthereon.

. Another object of the invention is to provide in carburetor No. 2 asuction responsive throttle .valve which controls the idl port of thiscarburetor and which maintains, while .in idl position, an idle fueldischarge in carburetor No, 2

"even though the throttle valve ofcarburetor No. 1 I

11 Claims. (Cl. 123-127) to the manifold through carburetor No. 2 beforethe suction controlled throttle, valve thereof is opened enough to feedgasoline from the main jet of carburetor N0. 2.

. A further object of the invention is to provide a counterweight forbiasing the throttle valveof carburetor No. 2 toward its closedpositionwhen it is disposed between its fully closed and a predetermined openposition and which biases the throttle valve of carburetor No. 2 towardits open position when disposed in a more. open position than saidpredetermined open position inorder to hold the throttle of carburetorNo. 2 from closing at a lower speed than that atwhich it would open froma closed position.

Any additional object of the invention is the provision of variable stopmechanism for positively limiting opening of the throttle valve ofcarburetor No. 2 in accordance with the extent of positive opening ofthe throttle valve of carburetor No. l, and which positively closes thethrottle valve of carburetor No. 2 simultaneously with, and inaccordance with, the extent. of positive closing of the throttle valveof carburetor No. l.

'5 Other objects of the invention are to provide in a carburetor whichmay be used as the single carburetor of an internal combustion engine, athrot-' 2 i tle valve which is responsive to total pressure differentialon its respectively opposite sidesyto pro-'- vid throttle valvemechanism and control apparatus therefor which when employed in a dualcarburetor system, or alone, serves to delay the transfer from idling tomain jet operation until sufiioient velocity has been obtained past 7the main jetto properly and smoothlyoperate the latter; toprovidemechanismof this kind which prevents detonation when operating atfull-load with a compression ratio substantially higher than normallyused andto thereby obtain an increase in thermal efliciency at part openthrottle.

An illustrative embodiment of the invention is shown in the accompanyingdrawing in which:

Fig. l is a fragmentary side; elevationalviewof an internal combustionengine havinga dual carburetor system equipped with throttle valveontrol apparatus embodyingthe invention.

. Fig. 2 is an enlarged horizontal sectional view of the throttle bodyportion of carburetor No. 2 taken on line 2-2 of Fig. 1.

Fig. 3 is a side'elevational view of the throttle body portionillustrated" in Fig. 2, showing the throttle valve'thereof in closedposition. Y

' Fig. 4 is a view similar to Fig; 3 showing the applied to an enginehaving an engine block I0 provided with a cylinder head H and an intakemanifold l2. The intake manifold 12 has a pair of inlet ducts or risersl3 and I 4 on whichare mounted primary and secondary carburetorshereinafter referred to as carburetor No. land carburetor-N0. 2respectively. Carburetors No; 1 and No. 2 have their air inletsconnectedwith-a common air cleaning and silencing device generallydesignated by the numeral 15. Each car-'- buretor includes asubstantially identical main body portion 86 which is provided on itslowerv ex.- tremity with a flange ll, adapted to be attached to acorresponding flange l8 at the upper end of-a throttle body I9. Eachthrottle body l9 has a flange 29 at its lower extremity adapted to besee cured by bolts to a corresponding flange 2| formed on the upperextremity of each of the risers l3 and M. A, y

The throttle body of the primary carburetor end of the shaft'22 is acontrol lever 24. With the exception of the throttle mechanism, the

throttle bodies of carburetors No. 1 and No. 2 are substantiallyidentical and, as shown in the illustrations of the throttle body of thecarburetor No. 2, each throttle body includes a central fuel mixturepassage 25. The wall of each throttle body is thickened at 26 andprovided with a downwardly extending-passage section 2'! whichcommunicates with a registering passage 28 leading through the wallstructure of the main body portion of the carburetor. The passagesection 21 communicates with a chamber 29 located in the thickened wallportion 26 of the throttle body and having a port 30, leading to thefuel mixture passage 25. The fuel mixture outlet port 3| whichcommunicates with the fuel mixture passage at a location below the port30 is also provided in the wall structure of the throttle body andconnected by angularly disposed passage sections 32 and 33 with thechamber 29. I The port 3| is adjustably controlled-by a needle valve 34having a stem portion extending through the passage section 33. Theabove mentioned fuel and air passages constitute an idle fuel mixtureand transfer system which is well known in the art.

Journalled in opposite apertures formed in the wall structure of thethrottle body of carburetor No.2 is a throttle shaft 35 on which ismounted an off-center throttle valve 36 which is adapted to be urgedtoward an open position by engine suction. The edge of the throttlevalve 35 registers with the lower portion of the port 30 when the valveis in closed position and is arranged to leave the upper portion of thisport open to admit air'under engine suction to the chamber 29 where itmixes with fuel supplied through the passage sections 21 and 28 from themain body of the carburetor in a conventional manner well known in theart of carburetion. When the valve is closed engine suction is appliedat the port'3l so as to induce the flow of fuel mixture into the fuelmixture passage 2'! at a point on the down stream side of the throttlevalve 36. As the throttle valve 36 is open its edge sweeps the port 30so as to gradually decrease the flow of air therethrough as the air flowpast the throttle increases thus effecting a gradual transfer from idlefuel mixture supply to the fuel mixture passage, to normal operatingconditions at open throttle.

The throttle shaft 35 extends through a boss 31 provided on the exteriorof the throttle body and it has an externally protruding end portion onwhich is fixed a counterweight 38 comprising a support disc 38' fixed tothe throttle shaft, and adjustable disc-shaped Weights 39'. The 'weights39' are adjustably fixed to the support plate 38' by screws 40' whichextend through arcuate slots 4! in the weights, the center of curvatureof the slots being offset from the centerof the support disc 38. Thecounterweight 38 is fixed to the throttle shaft 35 at a locationeccentric with respect to its center 39. As shown in Fig. 1, the center39 of the counterweight is disposed above the axes of the throttle shaftand to the right of a vertical plane containing the same when thethrottle valve 36 is in closed position. With this construction, thecounterweight tends to urge the throttle valve toward its closedposition until the throttle valve and the weight has been turnedcounterclockwise to a predetermined open position. When the throttlevalve is opened beyond said predetermined open position thecounterweight tends to urge the throttle valve toward a further openposition.

The throttle valve of carburetor No. 1 is positively controlled bothduring opening and closing movements by a rod 40 pivotally attached atone end to the lever 24 and at its opposite end to an arm 4! of a bellcrank42 which has a sec- 0nd arm .43 pivotally connected to an auxiliaryrod 44. The auxiliary rod 44 is adapted to be shifted by foot pressureapplied on an accelerato pedal 45 which bears against the opposite endof the rod 45 in order to rotate the bell crank 42 in a counterclockwisedirection as viewed in Fig. 1 and to thereby positively open thethrottle valve 23 of carburetor No, l. Closing movement of throttlevalve 23 of carburetor No. 1 is effected by the action of the spring 46bearing between the pedal 45 and the toe board 4'! on which theaccelerator is pivotally mounted at '38.

Opening and closing movement of the throttle valve 35 of carburetor No.2 is controlled by a variable stop mechanism including an arcuatelyshaped lever 49 pivotally mounted at 50 on a support extending from theside wall of the throttle body. Lever 49 has an inwardly extending pin5! on which is journalled a roller 52 for engaging an abutment 53mounted on the inner side of the counterweight 38 and disposed at anangle to the radius of a disc which comprises the counterweight. Theabutment 53 comprises an angleshaped bracket having a side disposed toengage the roller 52. The lever 49 has an end portion pivotallyconnected by a link 54 with a lever 55 which is pivotally mounted at 56in concentric relationship with the pivotal mounting of the bell crank62. The lever 55 includes a laterally extending flange 56 in which isthreaded an adjustable set screw 57. The end of the set screw 51registers with and is adapted to abut a flange 58 on the upstanding arm4| of the bell crank 42. A spring 58' normally urges the lever 55 in aclockwise direction about its pivotal support 56 thereby urging the link54 rightwardly as viewed in Fig. 1, in order to urge the roller 52rightwardly against the inclined abutment 53 so as to thereby yieldablyhold the throttle valv 36 in a closed position.- The set screw 51 isadjusted so that its end is spaced from the flange 58 on the bell crank42 in order to accommodate initial opening movement of the throttlevalve 23 of carburetor No. '1 during initial depression of theaccelerator pedal 45 without permitting the throttle valve 35 ofcarburetor No. 2 to move from its closed position. As soon as thethrottle valve of carburetor No. 1 has been opened beyond thispredetermined open position, the flange 58 of the bell crank engages theset screw 51 thereby rotating the lever 55 in a counterclockwisedirection against the action of the spring 58'.

Rotation of the lever 55 in a counterclockwise direction during thisfurther opening of the throttle valve of carburetor No, 1 from saidpredetermined open position causes the lever 49 to be correspondinglyrotated about its pivotal support 59 thereby moving the roller 52rightwardly so as to accommodate opening of the throttle valve 35 ofcarburetor No. 2 under the influence of engine suction existing in thefuel mixture passage of carburetor No. 2 and against the action of thecounterweight. When the throttle valve of carburetor No. l hasbeenopened and the lever 55 has been rotated in a counterclockwise directionsufficiently to accommodate rotation-of the throttle shaft 35 andcounterweight 38 to axes of the throttle shaft 35, as illustrated inFig. 4, then the counterweight assists in further opening movement ofthe throttle valve 35 as such movement is accommodated by furtherrightward movement of the roller 52.

With the foregoing control apparatus, the throttle valve of carburetorNo. 1 is initially opened a predetermined amount independently of thethrottle valve of carburetor No. 2 and while the latter throttle valveremains closed. The supply of an idling fuel mixture is continued underthese conditions by the idling system of carburetor No. 2 in order toassure a sufiicient supply of fuel to the air admitted to the manifoldthrough carburetor No. 2 during subsequent initial opening of thethrottle valve thereof and before the latter throttle valve is openedenough to feed fuel from the main jet of carburetor No. 2.

The counterweight biases the throttle valve of carburetor No. 2 towardits closed position when it is disposed between its fully closed and apredetermined open position. This counterweight also biases the throttlevalve of carburetor No. 2 toward its open position when disposed in amore open position than said predetermined open position. Thus thethrottle valve of carburetor No, 2 is held against closing at a lowerspeed of engine operation than that at which it would open from a closedposition.

The variable stop mechanism which controls the opening movement ofthrottle No. 2 does not positively open it but permits it to open inaccordance with the extent of positive opening of the throttle valv ofcarburetor No. 1 and then only when conditions exist which require thefeeding of fuel from the main jet of carburetor No. 2. This variablestop mechanism, however, positively closes the throttle valve ofcarburetor No. 2 simultaneously with, and an amount corresponding to theextent of positive closing of the throttle valve of carburetor No. 1.

With the foregoing fuel system and control therefor, mechanicaloperation at low speed is attainable by relying mainly on only one ofthe two carburetors to supply fuel mixture to the manifold I2. Duringhigh speed operation of the engine, the other carburetor isautomatically brought into operation.

The throttle and control mechanism of carburetor No. 2 can be employedto advantage in an internal combustion engine having a singlecarburetor. In this case, the accelerator controlled stop 49 serves tovariably limit opening of the throttle valv under control of theoperator. As the accelerator pedal is initially depressed, the stop 49is moved away from the abutment 53 thus accommodating opening of thethrottle valve under the action of the total pressure differential andagainst the action of the counterweight. This could be convenientlyaccomplished with the structure shown in the drawing by using the setscrew to secure the levers 55 and 4! together, the rod 40 being omitted.The counterweight may be conveniently disposed in angular position andpredetermined in weight and inertia to provide ample time for theattainment of sufiicient velocity past the main jet and flow of fuel tothe outlet of the latter to produce proper main jet operation before thesupply of fuel mixture by the idling system is discontinued. Thisobviates the condition of roughness in engine operation which resultsfrom suddenly, positively opening the throttle from its idle position.

bring the center 39 of the counterweight on the left side of thevertical plane containing the Throttle valve and control apparatusembodying invention may be used in a single carburetor system of anengine having an increased compression ratio to increase the thermalefiiciency during operation at part load. In this case, thecounterweight would be so disposed in angular position as to urge thethrottle valve to its closed position throughout its entire range ofthrottle movement. With this construction, there is provided arestriction to the flow of fuel mixture from the carburetor at allspeeds. This restriction permits the use of a, higher compression ratiowhich compensates for the decrease in maximum power output produced bythe restriction and also increases the thermal efliciency of the engine.

Although but one specific embodiment ofthe invention is herein shown anddescribed, it will be understood that various changes in the sequence ofoperations, steps and materials employed may be made without departingfrom the spirit of the invention.

It is claimed:

1. In an internal combustion engine having an intake manifold, a fuelmixture supply system including first and second carburetors each havinga fuel mixture outlet communicating with said intake manifold, athrottle valve in said first carburetor, control apparatus forpositively opening and closing the same at the will of an operator, anoff-center throttle valve freely rotatably mounted in saidsecondcarburetor adapted to open in response to the total pressuredifferential on respectively opposite sides thereof, control apparatusfor said last mentioned throttle valve operable by said controlapparatus of said first mentioned throttle valve throughout a portion ofits operating range, said second mentioned control apparatus including avariable abutment for positively closing said second mentioned throttlevalve simultaneously with closing movements of said first mentionedthrottle valve and so constructed and arranged as to variablyaccommodateopening of said second mentioned throttle valve by said pressuredifferential in accordance with the extent of opening of said firstmentioned throttle valve beyond a predetermined initially open position,and means for yieldably holding said last mentioned throttle valve inits closed position until a predetermined total pressure differential isapplied thereon in cluding a member so constructed and arranged as tourge said last mentioned throttle valve toward its closed positionduring the initial portion only of its range of opening movement.

, 2. In an internal combustion engine having an intake manifold, a fuelmixture supply system including first and second carburetors each havinga fuel mixture outlet communicating with said intake manifold, athrottle valve in said first carburetor, control apparatus forpositively opening and closing the same at the will of an opera tor, anoff-center throttle valve freely rotatably mounted in said secondcarburetor adapted to open in response to the total pressuredifferential on respectively opposite sides thereof, control apparatusfor said last mentioned throttle valve including an element engageablewith and operable by said first mentioned control apparatus during allbut its initial stage of throttle valve-opening movement, said secondmentioned control ap paratus including a variable abutment forpositively closing said second mentioned throttle valve simultaneouslywith closing movements --of said first'mentionedi throttle valve andsooon structed and arranged as to variably accommodate opening of saidsecond mentioned throttle valve by said pressure differential inaccordance with the extent of opening of said first mentioned throttlevalve beyond a predetermined initially open position, and meansconnected with said second mentioned throttle valve for biasing ittoward closed position when disposed between its closed and apredetermined open position and toward a further open position when openbeyond said predetermined position.

3. In an internal combustion engine having an intake manifold, a fuelmixture supply system including first and second carburetors each havinga fuel mixture outlet communicating with said intake manifold, athrottle valve in said first carburetor, control apparatus forpositively opening and closing the same at the will of an operator, anoff-center throttle valve freely rotatably mounted in said secondcarburetor adapted to open in response to the total pressuredifferential on respectively opposite sides thereof, means connectedwith said second mentioned throttle valve for biasing it toward closedposition when disposed between its closed and a predetermined openposition and toward a further open position when open beyond saidpredetermined position, and control apparatus for said last mentionedthrottle valve operable by said control apparatus of said firstmentioned throttle valve throughout a portion of its operating range,said second mentioned control apparatus including a variable abutmentfor positively closing said second mentioned throttle valvesimultaneously with closing movements of said first mentioned throttlevalve and so constructed and arranged as to variably accommodate openingof said second, mentioned throttle valve by said pressure differentialin accordance with the extent of opening of said first mentionedthrottle valve beyond a predetermined initially open position.

4. In an internal combustion engine having an intake manifold, a fuelmixture supply system ineluding first and second carburetors each havinga fuel mixture outlet communicating with said intake manifold, athrottle valve in said first carburetor, control apparatus forpositively opening 7 and closing the same at the will of an operator, an

off-center throttle valve freely rotatably mounted in said secondcarburetor adapted to open in response to the total pressuredifferential on respectively opposite sides thereof, means connectedwith said second mentioned throttle valve for biasing it toward closedposition when disposed between its closed and a predetermined openposition and toward a further open position when open beyond saidpredetermined position, and control apparatus for said second throttlevalve including an element engageable with and operable by said firstmentioned control apparatus during all but its initial stage of throttlevalve opening movement, said second mentioned control apparatusincluding a variable abutment for positively closing said secondmentioned throttle valve simuleach having a fuel mixture outletcommunicating with 'said manifold, manually operable means forpositively controlling the flow of fuel mixture from said primarycarburetor at the will of an operator, means for controlling the fiow offuel mixture from said secondary carburetor and the flow of liquid fuelfrom the idling jet thereof including a throttle valve in said outlet ofsaid secondary carburetor normally urged toward open position by thetotal pressure differential in said outlet on respectively oppositesides of said throttle valve during operation of said engine, and meansfor yieldably holding said throttle valve again t opening from itsidling position until said pressure differential reaches a predeterminedvalue including a weight member so constructed and arranged as toyieldably urge said throttle valve toward its closed position during aportion only of its range of opening movement.

6. In an internal combustion engine having an intake manifold, a fuelmixture supply system including a primary carburetor and a secondarycarburetor having main and idling fuel jets and each having a fuelmixture outlet communicating with said manifold, manually operable meansfor positively controlling the flow of fuel mixture from said primarycarburetor at the will of an operator including a throttle valve in theoutlet of said primary carburetor, means for controlling the flow offuel mixture from said secondary carburetor and the flow of liquid fuelfrom the idling jet thereof including a throttle Valve in said outlet ofsaid secondary carburetor normally urged toward open position by thetotal pressure differential in said outlet on respectively oppositesides of said throttle valve during operation of said engine, means foropposing opening of said second mentioned throttle valve until saidpressure differential reaches a predetermined value, mechanism forreleasably holding said second mentioned throttle valve closed, saidmechanism being engageable by said manually operable means duringopening of said first mentioned throttle valve thereby beyond apredetermined open position for releasing said second mentioned throttlevalve and thereafter variably limiting opening thereof in accordancewith opening movement of said first mentioned throttle, and means onsaid second mentioned throttle valve for biasing it toward a closedposition when disposed between its closed and a predetermined openposition and toward an open position when opened beyond saidpredetermined open position in order to hold said second mentionedthrottle valve against closing from a more open position than saidpredetermined position at a lower engine speed than that at which itopens from a closed position.

7. In an internal combustion engine having an intake manifold; a fuelmixture supply system including a primary carburetor and a secondarycarburetor having main and idling fuel jets and each having a fuelmixture outlet communicating with said manifold, manually operable meansfor positively controlling the flow of fuel mixture from said primarycarburetor including a throttle valve and control linkage for thelatter, an off-center throttle valve in said secondary carburetor havinga rotatively mounted shaft, said off-center throttle valve beingnormally urged toward open position by the total pressure differentialon respectively opposite sides thereof during operation of said engine,a weight member fixed to said shaft having its center of mass so locatedwith respect to the axis of said shaft as to urge said second mentionedthrottle valve toward a closed position when the latter is disposedbetween its closed and a predetermined open position and toward an openposition when opened beyond said predetermined open position, anabutment on said weight member, and means for variably limiting openingof said second mentioned throttle valve under said pressure differentialincluding a stop element rotatably mounted on said shaft and engageablewith said abutment, said latter means comprising a control linkage forrotating said stop and having an element engageable with the controllinkage of said manually operable means only when the latter is betweenits wide open throttle and a predetermined partially open throttlepositions, and including a spring for yieldably urging said stop intothrottle closing engagement with said abutment throughout the entirerange-of closing movement of said second mentioned throttle when thecontrol linkage of said manually operable control means is ineffectiveto urge said stop reversely.

8. In an internal combustion engine having an intake manifold, a fuelmixture supply system including a carburetor having main and idling fueljets and having a fuel mixture outlet communicating with said manifold,means for controllin tial in said outlet on its respectively oppositesides,

and means for retarding opening of said throttle valve from its idleposition in order that said main jet may be in normal operation asfeeding of fuel from said idle jet is discontinued, said means having amember so constructed and arranged as to urge said throttle valve towardits closed position throughout only a portion of its normal range ofopening movement.

9. In an internal combustion engine having an intake manifold, a fuelmixture supply system including a carburetor having main and idling fueljets and having a fuel mixture outlet communicating with said manifold,means for controlling the flow of fuel mixture from said outlet and theflow of liquid fuel from said idling jet including a throttle valve insaid outlet normally urged toward open position by the total pressuredifferential in said outlet on its respectively opposite sides, manuallyoperable means for positively urging said throttle valve toward itsclosed position and adapted to variably limit opening movement of saidthrottle, and means yieldably opposing opening of said throttl valve inresponse to said pressure differential during opening of said throttlevalve from its idling to a predetermined partially open position, saidlatter means being so constructed and arranged as to urge said throttlevalve in an opening direction after movement thereof beyond saidpredetermined partially open position.

10. In an internal combustion engine having an intake manifold, a fuelmixture supply system ineluding a carburetor having main and idling fueljets and having a fuel mixture outlet communicating with said manifold,means for controlling the flow of fuel mixture from said outlet and theflow of liquid fuel from said idling jet including a throttle valve insaid outlet normally urged toward open position by the total pressuredifferential in said outlet on its respectivelyopposite sides, manuallyoperable means for positively urging said throttle valve toward itsclosed position and adapted to variably limit opening movement of saidthrottle, and means yieldably opposing opening of said throttle valve inresponse to said pressure differential, said latter means including acounterbalancing member conveniently predeterminable in weight, angularposition and inertia.

11. In an internal combustion engine having a plurality of cylinders, anintake manifold having a plurality of outlet ports for supplying fuel tocertain of said cylinders, a pair of carburetors communicating with saidmanifold, a manually operated throttle for one of said carburetors, asecond throttle for the other carburetor, means responsive to suction asdetermined by the attainment of a predetermined engine speed foroperating said second throttle to open position, a common manuallyoperable control member for said throttle valves, means mechanicallyinterconnecting said throttle valves with each other and with saidcontrol member including an element for positively opening and closingsaid first throttle valve and an element for only positively closingsaid second throttle valve, and means connected with said secondmentioned throttle valve for biasing it toward closed position whendisposed between its closed and a predetermined open position and towarda further open position when open beyond said predetermined position.

THOMAS M. BALL. WALLACE E. ZIERER.

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